/*
 * Copyright 2010-2019 the Pacemaker project contributors
 *
 * The version control history for this file may have further details.
 *
 * This source code is licensed under the GNU General Public License version 2
 * or later (GPLv2+) WITHOUT ANY WARRANTY.
 */

#include <crm_internal.h>
#include "pacemakerd.h"

#include <pwd.h>
#include <grp.h>
#include <poll.h>
#include <stdio.h>
#include <stdbool.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/reboot.h>

#include <crm/crm.h>  /* indirectly: CRM_EX_* */
#include <crm/cib/internal.h>  /* cib_channel_ro */
#include <crm/msg_xml.h>
#include <crm/common/ipcs.h>
#include <crm/common/mainloop.h>
#include <crm/cluster/internal.h>
#include <crm/cluster.h>

#include <crm/common/ipc_internal.h>  /* PCMK__SPECIAL_PID*, ... */

#ifdef SUPPORT_COROSYNC
#include <corosync/cfg.h>
#endif

#include <dirent.h>
#include <ctype.h>

static gboolean pcmk_quorate = FALSE;
static gboolean fatal_error = FALSE;
static GMainLoop *mainloop = NULL;
static bool global_keep_tracking = false;

#define PCMK_PROCESS_CHECK_INTERVAL 5

static const char *local_name = NULL;
static uint32_t local_nodeid = 0;
static crm_trigger_t *shutdown_trigger = NULL;
static const char *pid_file = "/var/run/pacemaker.pid";

typedef struct pcmk_child_s {
    int pid;
    long flag;
    int start_seq;
    int respawn_count;
    gboolean respawn;
    const char *name;
    const char *uid;
    const char *command;
    const char *endpoint;  /* IPC server name */

    gboolean active_before_startup;
} pcmk_child_t;

/* Index into the array below */
#define PCMK_CHILD_CONTROLD  3

static pcmk_child_t pcmk_children[] = {
    {
        0, crm_proc_none,       0, 0, FALSE, "none",
        NULL, NULL
    },
    {
        0, crm_proc_execd,      3, 0, TRUE,  "pacemaker-execd",
        NULL, CRM_DAEMON_DIR "/pacemaker-execd",
        CRM_SYSTEM_LRMD
    },
    {
        0, crm_proc_based,      1, 0, TRUE,  "pacemaker-based",
        CRM_DAEMON_USER, CRM_DAEMON_DIR "/pacemaker-based",
        CIB_CHANNEL_RO
    },
    {
        0, crm_proc_controld,   6, 0, TRUE, "pacemaker-controld",
        CRM_DAEMON_USER, CRM_DAEMON_DIR "/pacemaker-controld",
        CRM_SYSTEM_CRMD
    },
    {
        0, crm_proc_attrd,      4, 0, TRUE, "pacemaker-attrd",
        CRM_DAEMON_USER, CRM_DAEMON_DIR "/pacemaker-attrd",
        T_ATTRD
    },
    {
        0, crm_proc_schedulerd, 5, 0, TRUE, "pacemaker-schedulerd",
        CRM_DAEMON_USER, CRM_DAEMON_DIR "/pacemaker-schedulerd",
        CRM_SYSTEM_PENGINE
    },
    {
        0, crm_proc_fenced,     2, 0, TRUE, "pacemaker-fenced",
        NULL, CRM_DAEMON_DIR "/pacemaker-fenced",
        "stonith-ng"
    },
};

static gboolean check_active_before_startup_processes(gpointer user_data);
static int pcmk_child_active(pcmk_child_t *child);
static gboolean start_child(pcmk_child_t * child);
static gboolean update_node_processes(uint32_t id, const char *uname,
                                      uint32_t procs);
void update_process_clients(crm_client_t *client);

static uint32_t
get_process_list(void)
{
    int lpc = 0;
    uint32_t procs = crm_get_cluster_proc();

    for (lpc = 0; lpc < SIZEOF(pcmk_children); lpc++) {
        if (pcmk_children[lpc].pid != 0) {
            procs |= pcmk_children[lpc].flag;
        }
    }
    return procs;
}

static void
pcmk_process_exit(pcmk_child_t * child)
{
    child->pid = 0;
    child->active_before_startup = FALSE;

    /* Broadcast the fact that one of our processes died ASAP
     *
     * Try to get some logging of the cause out first though
     * because we're probably about to get fenced
     *
     * Potentially do this only if respawn_count > N
     * to allow for local recovery
     */
    update_node_processes(local_nodeid, NULL, get_process_list());

    child->respawn_count += 1;
    if (child->respawn_count > MAX_RESPAWN) {
        crm_err("Child respawn count exceeded by %s", child->name);
        child->respawn = FALSE;
    }

    if (shutdown_trigger) {
        /* resume step-wise shutdown (returned TRUE yields no parallelizing) */
        mainloop_set_trigger(shutdown_trigger);
        /* intended to speed up propagating expected lay-off of the daemons? */
        update_node_processes(local_nodeid, NULL, get_process_list());

    } else if (!child->respawn) {
        /* nothing to do */

    } else if (crm_is_true(getenv("PCMK_fail_fast"))) {
        crm_err("Rebooting system because of %s", child->name);
        pcmk_panic(__FUNCTION__);

    } else if (pcmk_child_active(child) == 1) {
        crm_warn("One-off suppressing strict respawning of a child process %s,"
                 " appears alright per %s IPC end-point",
                 child->name, child->endpoint);
        /* need to monitor how it evolves, and start new process if badly */
        child->active_before_startup = TRUE;
        if (!global_keep_tracking) {
            global_keep_tracking = true;
            g_timeout_add_seconds(PCMK_PROCESS_CHECK_INTERVAL,
                                  check_active_before_startup_processes, NULL);
        }

    } else {
        crm_notice("Respawning failed child process: %s", child->name);
        start_child(child);
    }
}

static void pcmk_exit_with_cluster(int exitcode)
{
#ifdef SUPPORT_COROSYNC
    corosync_cfg_handle_t cfg_handle;
    cs_error_t err;

    if (exitcode == CRM_EX_FATAL) {
	    crm_info("Asking Corosync to shut down");
	    err = corosync_cfg_initialize(&cfg_handle, NULL);
	    if (err != CS_OK) {
		    crm_warn("Unable to open handle to corosync to close it down. err=%d", err);
	    }
	    err = corosync_cfg_try_shutdown(cfg_handle, COROSYNC_CFG_SHUTDOWN_FLAG_IMMEDIATE);
	    if (err != CS_OK) {
		    crm_warn("Corosync shutdown failed. err=%d", err);
	    }
	    corosync_cfg_finalize(cfg_handle);
    }
#endif
    crm_exit(exitcode);
}

static void
pcmk_child_exit(mainloop_child_t * p, pid_t pid, int core, int signo, int exitcode)
{
    pcmk_child_t *child = mainloop_child_userdata(p);
    const char *name = mainloop_child_name(p);

    if (signo) {
        do_crm_log(((signo == SIGKILL)? LOG_WARNING : LOG_ERR),
                   "%s[%d] terminated with signal %d (core=%d)",
                   name, pid, signo, core);

    } else {
        switch(exitcode) {
            case CRM_EX_OK:
                crm_info("%s[%d] exited with status %d (%s)",
                         name, pid, exitcode, crm_exit_str(exitcode));
                break;

            case CRM_EX_FATAL:
                crm_warn("Shutting cluster down because %s[%d] had fatal failure",
                         name, pid);
                child->respawn = FALSE;
                fatal_error = TRUE;
                pcmk_shutdown(SIGTERM);
                break;

            case CRM_EX_PANIC:
                do_crm_log_always(LOG_EMERG,
                                  "%s[%d] instructed the machine to reset",
                                  name, pid);
                child->respawn = FALSE;
                fatal_error = TRUE;
                pcmk_panic(__FUNCTION__);
                pcmk_shutdown(SIGTERM);
                break;

            default:
                crm_err("%s[%d] exited with status %d (%s)",
                        name, pid, exitcode, crm_exit_str(exitcode));
                break;
        }
    }

    pcmk_process_exit(child);
}

static gboolean
stop_child(pcmk_child_t * child, int signal)
{
    if (signal == 0) {
        signal = SIGTERM;
    }

    /* why to skip PID of 1?
       - FreeBSD ~ how untrackable process behind IPC is masqueraded as
       - elsewhere: how "init" task is designated; in particular, in systemd
         arrangement of socket-based activation, this is pretty real */
    if (child->command == NULL || child->pid == PCMK__SPECIAL_PID) {
        crm_debug("Nothing to do for child \"%s\" (process %lld)",
                  child->name, (long long) PCMK__SPECIAL_PID_AS_0(child->pid));
        return TRUE;
    }

    if (child->pid <= 0) {
        crm_trace("Client %s not running", child->name);
        return TRUE;
    }

    errno = 0;
    if (kill(child->pid, signal) == 0) {
        crm_notice("Stopping %s "CRM_XS" sent signal %d to process %d",
                   child->name, signal, child->pid);

    } else {
        crm_perror(LOG_ERR, "Could not stop %s (process %d) with signal %d",
                   child->name, child->pid, signal);
    }

    return TRUE;
}

static char *opts_default[] = { NULL, NULL };
static char *opts_vgrind[] = { NULL, NULL, NULL, NULL, NULL };

/* TODO once libqb is taught to juggle with IPC end-points carried over as
        bare file descriptor (https://github.com/ClusterLabs/libqb/issues/325)
        it shall hand over these descriptors here if/once they are successfully
        pre-opened in (presumably) pcmk_child_active, to avoid any remaining
        room for races */
static gboolean
start_child(pcmk_child_t * child)
{
    uid_t uid = 0;
    gid_t gid = 0;
    gboolean use_valgrind = FALSE;
    gboolean use_callgrind = FALSE;
    const char *devnull = "/dev/null";
    const char *env_valgrind = getenv("PCMK_valgrind_enabled");
    const char *env_callgrind = getenv("PCMK_callgrind_enabled");

    child->active_before_startup = FALSE;

    if (child->command == NULL) {
        crm_info("Nothing to do for child \"%s\"", child->name);
        return TRUE;
    }

    if (env_callgrind != NULL && crm_is_true(env_callgrind)) {
        use_callgrind = TRUE;
        use_valgrind = TRUE;

    } else if (env_callgrind != NULL && strstr(env_callgrind, child->name)) {
        use_callgrind = TRUE;
        use_valgrind = TRUE;

    } else if (env_valgrind != NULL && crm_is_true(env_valgrind)) {
        use_valgrind = TRUE;

    } else if (env_valgrind != NULL && strstr(env_valgrind, child->name)) {
        use_valgrind = TRUE;
    }

    if (use_valgrind && strlen(VALGRIND_BIN) == 0) {
        crm_warn("Cannot enable valgrind for %s:"
                 " The location of the valgrind binary is unknown", child->name);
        use_valgrind = FALSE;
    }

    if (child->uid) {
        if (crm_user_lookup(child->uid, &uid, &gid) < 0) {
            crm_err("Invalid user (%s) for %s: not found", child->uid, child->name);
            return FALSE;
        }
        crm_info("Using uid=%u and group=%u for process %s", uid, gid, child->name);
    }

    child->pid = fork();
    CRM_ASSERT(child->pid != -1);

    if (child->pid > 0) {
        /* parent */
        mainloop_child_add(child->pid, 0, child->name, child, pcmk_child_exit);

        crm_info("Forked child %d for process %s%s", child->pid, child->name,
                 use_valgrind ? " (valgrind enabled: " VALGRIND_BIN ")" : "");
        update_node_processes(local_nodeid, NULL, get_process_list());
        return TRUE;

    } else {
        /* Start a new session */
        (void)setsid();

        /* Setup the two alternate arg arrays */
        opts_vgrind[0] = strdup(VALGRIND_BIN);
        if (use_callgrind) {
            opts_vgrind[1] = strdup("--tool=callgrind");
            opts_vgrind[2] = strdup("--callgrind-out-file=" CRM_STATE_DIR "/callgrind.out.%p");
            opts_vgrind[3] = strdup(child->command);
            opts_vgrind[4] = NULL;
        } else {
            opts_vgrind[1] = strdup(child->command);
            opts_vgrind[2] = NULL;
            opts_vgrind[3] = NULL;
            opts_vgrind[4] = NULL;
        }
        opts_default[0] = strdup(child->command);

        if(gid) {
            // Whether we need root group access to talk to cluster layer
            bool need_root_group = TRUE;

            if (is_corosync_cluster()) {
                /* Corosync clusters can drop root group access, because we set
                 * uidgid.gid.${gid}=1 via CMAP, which allows these processes to
                 * connect to corosync.
                 */
                need_root_group = FALSE;
            }

            // Drop root group access if not needed
            if (!need_root_group && (setgid(gid) < 0)) {
                crm_perror(LOG_ERR, "Could not set group to %d", gid);
            }

            /* Initialize supplementary groups to only those always granted to
             * the user, plus haclient (so we can access IPC).
             */
            if (initgroups(child->uid, gid) < 0) {
                crm_err("Cannot initialize groups for %s: %s (%d)", child->uid, pcmk_strerror(errno), errno);
            }
        }

        if (uid && setuid(uid) < 0) {
            crm_perror(LOG_ERR, "Could not set user to %d (%s)", uid, child->uid);
        }

        pcmk__close_fds_in_child(true);

        (void)open(devnull, O_RDONLY);  /* Stdin:  fd 0 */
        (void)open(devnull, O_WRONLY);  /* Stdout: fd 1 */
        (void)open(devnull, O_WRONLY);  /* Stderr: fd 2 */

        if (use_valgrind) {
            (void)execvp(VALGRIND_BIN, opts_vgrind);
        } else {
            (void)execvp(child->command, opts_default);
        }
        crm_perror(LOG_ERR, "FATAL: Cannot exec %s", child->command);
        crm_exit(CRM_EX_FATAL);
    }
    return TRUE;                /* never reached */
}

static gboolean
escalate_shutdown(gpointer data)
{

    pcmk_child_t *child = data;

    if (child->pid == PCMK__SPECIAL_PID) {
        pcmk_process_exit(child);

    } else if (child->pid) {
        /* Use SIGSEGV instead of SIGKILL to create a core so we can see what it was up to */
        crm_err("Child %s not terminating in a timely manner, forcing", child->name);
        stop_child(child, SIGSEGV);
    }
    return FALSE;
}

#define SHUTDOWN_ESCALATION_PERIOD 180000  /* 3m */

static gboolean
pcmk_shutdown_worker(gpointer user_data)
{
    static int phase = 0;
    static time_t next_log = 0;
    static int max = SIZEOF(pcmk_children);

    int lpc = 0;

    if (phase == 0) {
        crm_notice("Shutting down Pacemaker");
        phase = max;
    }

    for (; phase > 0; phase--) {
        /* Don't stop anything with start_seq < 1 */

        for (lpc = max - 1; lpc >= 0; lpc--) {
            pcmk_child_t *child = &(pcmk_children[lpc]);

            if (phase != child->start_seq) {
                continue;
            }

            if (child->pid) {
                time_t now = time(NULL);

                if (child->respawn) {
                    if (child->pid == PCMK__SPECIAL_PID) {
                        crm_warn("The process behind %s IPC cannot be"
                                 " terminated, so either wait the graceful"
                                 " period of %ld s for its native termination"
                                 " if it vitally depends on some other daemons"
                                 " going down in a controlled way already,"
                                 " or locate and kill the correct %s process"
                                 " on your own; set PCMK_fail_fast=1 to avoid"
                                 " this altogether next time around",
                                 child->name, (long) SHUTDOWN_ESCALATION_PERIOD,
                                 child->command);
                    }
                    next_log = now + 30;
                    child->respawn = FALSE;
                    stop_child(child, SIGTERM);
                    if (phase < pcmk_children[PCMK_CHILD_CONTROLD].start_seq) {
                        g_timeout_add(SHUTDOWN_ESCALATION_PERIOD,
                                      escalate_shutdown, child);
                    }

                } else if (now >= next_log) {
                    next_log = now + 30;
                    crm_notice("Still waiting for %s to terminate "
                               CRM_XS " pid=%d seq=%d",
                               child->name, child->pid, child->start_seq);
                }
                return TRUE;
            }

            /* cleanup */
            crm_debug("%s confirmed stopped", child->name);
            child->pid = 0;
        }
    }

    /* send_cluster_id(); */
    crm_notice("Shutdown complete");

    {
        const char *delay = daemon_option("shutdown_delay");
        if(delay) {
            sync();
            sleep(crm_get_msec(delay) / 1000);
        }
    }

    g_main_loop_quit(mainloop);

    if (fatal_error) {
        crm_notice("Shutting down and staying down after fatal error");
        pcmk_exit_with_cluster(CRM_EX_FATAL);
    }

    return TRUE;
}

static void
pcmk_ignore(int nsig)
{
    crm_info("Ignoring signal %s (%d)", strsignal(nsig), nsig);
}

static void
pcmk_sigquit(int nsig)
{
    pcmk_panic(__FUNCTION__);
}

void
pcmk_shutdown(int nsig)
{
    if (shutdown_trigger == NULL) {
        shutdown_trigger = mainloop_add_trigger(G_PRIORITY_HIGH, pcmk_shutdown_worker, NULL);
    }
    mainloop_set_trigger(shutdown_trigger);
}

static int32_t
pcmk_ipc_accept(qb_ipcs_connection_t * c, uid_t uid, gid_t gid)
{
    crm_trace("Connection %p", c);
    if (crm_client_new(c, uid, gid) == NULL) {
        return -EIO;
    }
    return 0;
}

static void
pcmk_ipc_created(qb_ipcs_connection_t * c)
{
    crm_trace("Connection %p", c);
}

/* Exit code means? */
static int32_t
pcmk_ipc_dispatch(qb_ipcs_connection_t * qbc, void *data, size_t size)
{
    uint32_t id = 0;
    uint32_t flags = 0;
    const char *task = NULL;
    crm_client_t *c = crm_client_get(qbc);
    xmlNode *msg = crm_ipcs_recv(c, data, size, &id, &flags);

    crm_ipcs_send_ack(c, id, flags, "ack", __FUNCTION__, __LINE__);
    if (msg == NULL) {
        return 0;
    }

    task = crm_element_value(msg, F_CRM_TASK);
    if (crm_str_eq(task, CRM_OP_QUIT, TRUE)) {
        /* Time to quit */
        crm_notice("Shutting down in response to ticket %s (%s)",
                   crm_element_value(msg, F_CRM_REFERENCE), crm_element_value(msg, F_CRM_ORIGIN));
        pcmk_shutdown(15);

    } else if (crm_str_eq(task, CRM_OP_RM_NODE_CACHE, TRUE)) {
        /* Send to everyone */
        struct iovec *iov;
        int id = 0;
        const char *name = NULL;

        crm_element_value_int(msg, XML_ATTR_ID, &id);
        name = crm_element_value(msg, XML_ATTR_UNAME);
        crm_notice("Instructing peers to remove references to node %s/%u", name, id);

        iov = calloc(1, sizeof(struct iovec));
        iov->iov_base = dump_xml_unformatted(msg);
        iov->iov_len = 1 + strlen(iov->iov_base);
        send_cpg_iov(iov);

    } else {
        update_process_clients(c);
    }

    free_xml(msg);
    return 0;
}

/* Error code means? */
static int32_t
pcmk_ipc_closed(qb_ipcs_connection_t * c)
{
    crm_client_t *client = crm_client_get(c);

    if (client == NULL) {
        return 0;
    }
    crm_trace("Connection %p", c);
    crm_client_destroy(client);
    return 0;
}

static void
pcmk_ipc_destroy(qb_ipcs_connection_t * c)
{
    crm_trace("Connection %p", c);
    pcmk_ipc_closed(c);
}

struct qb_ipcs_service_handlers mcp_ipc_callbacks = {
    .connection_accept = pcmk_ipc_accept,
    .connection_created = pcmk_ipc_created,
    .msg_process = pcmk_ipc_dispatch,
    .connection_closed = pcmk_ipc_closed,
    .connection_destroyed = pcmk_ipc_destroy
};

/*!
 * \internal
 * \brief Send an XML message with process list of all known peers to client(s)
 *
 * \param[in] client  Send message to this client, or all clients if NULL
 */
void
update_process_clients(crm_client_t *client)
{
    GHashTableIter iter;
    crm_node_t *node = NULL;
    xmlNode *update = create_xml_node(NULL, "nodes");

    if (is_corosync_cluster()) {
        crm_xml_add_int(update, "quorate", pcmk_quorate);
    }

    g_hash_table_iter_init(&iter, crm_peer_cache);
    while (g_hash_table_iter_next(&iter, NULL, (gpointer *) & node)) {
        xmlNode *xml = create_xml_node(update, "node");

        crm_xml_add_int(xml, "id", node->id);
        crm_xml_add(xml, "uname", node->uname);
        crm_xml_add(xml, "state", node->state);
        crm_xml_add_int(xml, "processes", node->processes);
    }

    if(client) {
        crm_trace("Sending process list to client %s", client->id);
        crm_ipcs_send(client, 0, update, crm_ipc_server_event);

    } else {
        crm_trace("Sending process list to %d clients", crm_hash_table_size(client_connections));
        g_hash_table_iter_init(&iter, client_connections);
        while (g_hash_table_iter_next(&iter, NULL, (gpointer *) & client)) {
            crm_ipcs_send(client, 0, update, crm_ipc_server_event);
        }
    }

    free_xml(update);
}

/*!
 * \internal
 * \brief Send a CPG message with local node's process list to all peers
 */
static void
update_process_peers(void)
{
    /* Do nothing for corosync-2 based clusters */

    struct iovec *iov = calloc(1, sizeof(struct iovec));

    CRM_ASSERT(iov);
    if (local_name) {
        iov->iov_base = crm_strdup_printf("<node uname=\"%s\" proclist=\"%u\"/>",
                                          local_name, get_process_list());
    } else {
        iov->iov_base = crm_strdup_printf("<node proclist=\"%u\"/>",
                                          get_process_list());
    }
    iov->iov_len = strlen(iov->iov_base) + 1;
    crm_trace("Sending %s", (char*) iov->iov_base);
    send_cpg_iov(iov);
}

/*!
 * \internal
 * \brief Update a node's process list, notifying clients and peers if needed
 *
 * \param[in] id     Node ID of affected node
 * \param[in] uname  Uname of affected node
 * \param[in] procs  Affected node's process list mask
 *
 * \return TRUE if the process list changed, FALSE otherwise
 */
static gboolean
update_node_processes(uint32_t id, const char *uname, uint32_t procs)
{
    gboolean changed = FALSE;
    crm_node_t *node = crm_get_peer(id, uname);

    if (procs != 0) {
        if (procs != node->processes) {
            crm_debug("Node %s now has process list: %.32x (was %.32x)",
                      node->uname, procs, node->processes);
            node->processes = procs;
            changed = TRUE;

            /* If local node's processes have changed, notify clients/peers */
            if (id == local_nodeid) {
                update_process_clients(NULL);
                update_process_peers();
            }

        } else {
            crm_trace("Node %s still has process list: %.32x", node->uname, procs);
        }
    }
    return changed;
}


/* *INDENT-OFF* */
static struct crm_option long_options[] = {
    /* Top-level Options */
    {"help",           0, 0, '?', "\tThis text"},
    {"version",        0, 0, '$', "\tVersion information"  },
    {"verbose",        0, 0, 'V', "\tIncrease debug output"},
    {"shutdown",       0, 0, 'S', "\tInstruct Pacemaker to shutdown on this machine"},
    {"features",       0, 0, 'F', "\tDisplay the full version and list of features Pacemaker was built with"},

    {"-spacer-",       1, 0, '-', "\nAdditional Options:"},
    {"foreground",     0, 0, 'f', "\t(Ignored) Pacemaker always runs in the foreground"},
    {"pid-file",       1, 0, 'p', "\t(Ignored) Daemon pid file location"},
    {"standby",        0, 0, 's', "\tStart node in standby state"},

    {NULL, 0, 0, 0}
};
/* *INDENT-ON* */

static void
mcp_chown(const char *path, uid_t uid, gid_t gid)
{
    int rc = chown(path, uid, gid);

    if (rc < 0) {
        crm_warn("Cannot change the ownership of %s to user %s and gid %d: %s",
                 path, CRM_DAEMON_USER, gid, pcmk_strerror(errno));
    }
}

/*!
 * \internal
 * \brief Check the liveness of the child based on IPC name and PID if tracked
 *
 * \param[inout] child  Child tracked data
 *
 * \return 0 if no trace of child's liveness detected (while it is detectable
 *         to begin with, at least according to one of the two properties),
 *         1 if everything is fine, 2 if it's up per PID, but not per IPC
 *         end-point (still starting?), -1 on error, and -2 when the child
 *         (its IPC) blocked with an unauthorized process (log message
 *         emitted in both latter cases)
 *
 * \note This function doesn't modify any of \p child members but \c pid,
 *       and is not actively toying with processes as such but invoking
 *       \c stop_child in one particular case (there's for some reason
 *       a different authentic holder of the IPC end-point).
 */
static int
pcmk_child_active(pcmk_child_t *child) {
    static uid_t cl_uid = 0;
    static gid_t cl_gid = 0;
    const uid_t root_uid = 0;
    const gid_t root_gid = 0;
    const uid_t *ref_uid;
    const gid_t *ref_gid;
    int ret = 0;
    pid_t ipc_pid = 0;

    if (child->endpoint == NULL
            && (child->pid <= 0 || child->pid == PCMK__SPECIAL_PID)) {
        crm_err("Cannot track child %s for missing both API end-point and PID",
                child->name);
        ret = -1;  /* misuse of the function when child is not trackable */

    } else if (child->endpoint != NULL) {

        ref_uid = (child->uid != NULL) ? &cl_uid : &root_uid;
        ref_gid = (child->uid != NULL) ? &cl_gid : &root_gid;

        if (child->uid != NULL && !cl_uid && !cl_gid
                && crm_user_lookup(CRM_DAEMON_USER, &cl_uid, &cl_gid) < 0) {
            crm_err("Could not find user and group IDs for user %s",
                    CRM_DAEMON_USER);
            ret = -1;
        } else if ((ret = pcmk__ipc_is_authentic_process_active(child->endpoint,
                                                                *ref_uid, *ref_gid,
                                                                &ipc_pid)) < 0) {
            /* game over */
        } else if (child->pid <= 0) {
            /* hit new child to be initialized, or reset to zero
               and investigate further for ret == 0 */
            child->pid = ipc_pid;
        } else if (ipc_pid && child->pid != ipc_pid) {
            /* ultimately strange for ret == 1; either way, investigate */
            ret = 0;
        }
    }

    if (!ret) {
        /* when no IPC based liveness detected (incl. if ever a child without
           IPC is tracked), or detected for a different _authentic_ process;
           safe on FreeBSD since the only change possible from a proper child's
           PID into "special" PID of 1 behind more loosely related process */
        ret = crm_pid_active(child->pid, child->name);
        if (ipc_pid && (ret != 1
                        || ipc_pid == PCMK__SPECIAL_PID
                        || crm_pid_active(ipc_pid, child->name) == 1)) {
            if (ret == 1) {
                /* assume there's no forking-while-retaining-IPC-socket
                   involved in the "children's" lifecycle, hence that the
                   tracking got out of sync purely because of some external
                   (esotheric?) forces (user initiated process "refresh" by
                   force? or intentionally racing on start-up, even?), and
                   that switching over to this other detected, authentic
                   instance with an IPC already in possession is a better
                   trade-off than "neutralizing" it first so as to give
                   either the original or possibly a new to-be-spawned
                   daemon process a leeway for operation, which would
                   otherwise have to be carried out */
                /* not possessing IPC, afterall (what about corosync CPG?) */
                stop_child(child, SIGKILL);
            } else {
                ret = 1;
            }
            child->pid = ipc_pid;
        } else if (ret == 1) {
            ret = 2;  /* up per PID, but not per IPC (still starting?) */
        } else if (!child->pid && ret == -1) {
            ret = 0;  /* correct -1 on FreeBSD from above back to 0 */
        }
    }

    return ret;
}

static gboolean
check_active_before_startup_processes(gpointer user_data)
{
    int start_seq = 1, lpc = 0;
    static int max = SIZEOF(pcmk_children);
    gboolean keep_tracking = FALSE;

    for (start_seq = 1; start_seq < max; start_seq++) {
        for (lpc = 0; lpc < max; lpc++) {
            if (pcmk_children[lpc].active_before_startup == FALSE) {
                /* we are already tracking it as a child process. */
                continue;
            } else if (start_seq != pcmk_children[lpc].start_seq) {
                continue;
            } else {
                const char *name = pcmk_children[lpc].name;
                int ret;

                switch ((ret = pcmk_child_active(&pcmk_children[lpc]))) {
                    case 1:
                        break;
                    case 0:
                    case 2:  /* this very case: it was OK once already */
                        if (pcmk_children[lpc].respawn == TRUE) {
                            /* presumably after crash, hence critical */
                            crm_crit("Process %s terminated (pid=%lld)%s", \
                                     name, (long long)
                                     PCMK__SPECIAL_PID_AS_0(pcmk_children[lpc].pid),
                                     ret ? ", at least per IPC end-point that went AWOL"
                                         : "");
                        } else {
                            /* orderly shutdown */
                            crm_notice("Process %s terminated (pid=%lld)%s", \
                                       name, (long long)
                                       PCMK__SPECIAL_PID_AS_0(pcmk_children[lpc].pid),
                                       ret ? ", at least per IPC end-point that went AWOL"
                                           : "");
                        }
                        pcmk_process_exit(&(pcmk_children[lpc]));
                        continue;
                    default:
                        crm_crit("Unexpected value from pcmk_child_active:"
                                 " %d (pid=%lld)", ret,
                                 (long long) PCMK__SPECIAL_PID_AS_0(
                                                 pcmk_children[lpc].pid));
                        /* fall through */
                    case -1:
                    case -2:
                        /* message(s) already emitted */
                        crm_exit(CRM_EX_FATAL);
                        break;  /* static analysis/noreturn */
                }
            }
            /* at least one of the processes found at startup
             * is still going, so keep this recurring timer around */
            keep_tracking = TRUE;
        }
    }

    global_keep_tracking = keep_tracking;
    return keep_tracking;
}

/*!
 * \internal
 * \brief Initial one-off check of the pre-existing "child" processes
 *
 * With "child" process, we mean the subdaemon that defines an API end-point
 * (all of them do as of the comment) -- the possible complement is skipped
 * as it is deemed it has no such shared resources to cause conflicts about,
 * hence it can presumably be started anew without hesitation.
 * If that won't hold true in the future, the concept of a shared resource
 * will have to be generalized beyond the API end-point.
 *
 * For boundary cases that the "child" is still starting (IPC end-point is yet
 * to be witnessed), or more rarely (practically FreeBSD only), when there's
 * a pre-existing "untrackable" authentic process, we give the situation some
 * time to possibly unfold in the right direction, meaning that said socket
 * will appear or the unattainable process will disappear per the observable
 * IPC, respectively.
 *
 * \return 0 if no such "child" process found, positive number X when X
 *         "children" detected, -1 on an internal error, -2 when any
 *         would-be-used IPC is blocked with an unauthorized process
 *
 * \note Since this gets run at the very start, \c respawn_count fields
 *       for particular children get temporarily overloaded with "rounds
 *       of waiting" tracking, restored once we are about to finish with
 *       success (i.e. returning value >=0) and will remain unrestored
 *       otherwise.  One way to suppress liveness detection logic for
 *       particular child is to set the said value to a negative number.
 */
#define WAIT_TRIES 4  /* together with interleaved sleeps, worst case ~ 1s */
static int
find_and_track_existing_processes(void)
{
    unsigned tracking = 0U;
    bool wait_in_progress;
    int cur;
    size_t i, rounds;

    for (rounds = 1; rounds <= WAIT_TRIES; rounds++) {
        wait_in_progress = false;
        for (i = 0; i < SIZEOF(pcmk_children); i++) {
            if (!pcmk_children[i].endpoint
                    || pcmk_children[i].respawn_count < 0
                    || !(cur = pcmk_child_active(&pcmk_children[i]))) {
                /* as a speculation, don't give up in the context of
                   pcmk_child_active check if there are more rounds to
                   come for other reasons, but don't artificially wait just
                   because of this, since we would preferably start ASAP */
                continue;
            }
            pcmk_children[i].respawn_count = rounds;
            switch (cur) {
                case 1:
                    if (pcmk_children[i].pid == PCMK__SPECIAL_PID) {
                        if (crm_is_true(getenv("PCMK_fail_fast"))) {
                            crm_crit("Cannot reliably track pre-existing"
                                     " authentic process behind %s IPC on this"
                                     " platform and PCMK_fail_fast requested",
                                     pcmk_children[i].endpoint);
                            return -1;
                        } else if (pcmk_children[i].respawn_count == WAIT_TRIES) {
                            crm_notice("Assuming pre-existing authentic, though"
                                       " on this platform untrackable, process"
                                       " behind %s IPC is stable (was in %d"
                                       " previous samples) so rather than"
                                       " bailing out (PCMK_fail_fast not"
                                       " requested), we just switch to a less"
                                       " optimal IPC liveness monitoring"
                                       " (not very suitable for heavy load)",
                                       pcmk_children[i].name, WAIT_TRIES - 1);
                            crm_warn("The process behind %s IPC cannot be"
                                     " terminated, so the overall shutdown"
                                     " will get delayed implicitly (%ld s),"
                                     " which serves as a graceful period for"
                                     " its native termination if it vitally"
                                     " depends on some other daemons going"
                                     " down in a controlled way already",
                                     pcmk_children[i].name,
                                     (long) SHUTDOWN_ESCALATION_PERIOD);
                        } else {
                            wait_in_progress = true;
                            crm_warn("Cannot reliably track pre-existing"
                                     " authentic process behind %s IPC on this"
                                     " platform, can still disappear in %d"
                                     " attempt(s)", pcmk_children[i].endpoint,
                                     WAIT_TRIES - pcmk_children[i].respawn_count);
                            continue;
                        }
                    }
                    crm_notice("Tracking existing %s process (pid=%lld)",
                               pcmk_children[i].name,
                               (long long) PCMK__SPECIAL_PID_AS_0(
                                               pcmk_children[i].pid));
                    pcmk_children[i].respawn_count = -1;  /* 0~keep watching */
                    pcmk_children[i].active_before_startup = TRUE;
                    tracking++;
                    break;
                case 2:
                    if (pcmk_children[i].respawn_count == WAIT_TRIES) {
                        crm_crit("%s IPC end-point for existing authentic"
                                 " process %lld did not (re)appear",
                                 pcmk_children[i].endpoint,
                                 (long long) PCMK__SPECIAL_PID_AS_0(
                                                 pcmk_children[i].pid));
                        return -1;
                    }
                    wait_in_progress = true;
                    crm_warn("Cannot find %s IPC end-point for existing"
                             " authentic process %lld, can still (re)appear"
                             " in %d attempts (?)",
                             pcmk_children[i].endpoint,
                             (long long) PCMK__SPECIAL_PID_AS_0(
                                             pcmk_children[i].pid),
                             WAIT_TRIES - pcmk_children[i].respawn_count);
                    continue;
                case -1:
                case -2:
                    return cur;  /* messages already emitted */
                default:
                    crm_crit("Unexpected condition"CRM_XS"cur=%d", cur);
                    return -1;  /* unexpected condition */
            }
        }
        if (!wait_in_progress) {
            break;
        }
        (void) poll(NULL, 0, 250);  /* a bit for changes to possibly happen */
    }
    for (i = 0; i < SIZEOF(pcmk_children); i++) {
        pcmk_children[i].respawn_count = 0;  /* restore pristine state */
    }

    if (tracking) {
        g_timeout_add_seconds(PCMK_PROCESS_CHECK_INTERVAL,
                              check_active_before_startup_processes, NULL);
    }
    return (tracking > INT_MAX) ? INT_MAX : tracking;
}

static void
init_children_processes(void)
{
    int start_seq = 1, lpc = 0;
    static int max = SIZEOF(pcmk_children);

    /* start any children that have not been detected */
    for (start_seq = 1; start_seq < max; start_seq++) {
        /* don't start anything with start_seq < 1 */
        for (lpc = 0; lpc < max; lpc++) {
            if (pcmk_children[lpc].pid) {
                /* we are already tracking it */
                continue;
            }

            if (start_seq == pcmk_children[lpc].start_seq) {
                start_child(&(pcmk_children[lpc]));
            }
        }
    }

    /* From this point on, any daemons being started will be due to
     * respawning rather than node start.
     *
     * This may be useful for the daemons to know
     */
    setenv("PCMK_respawned", "true", 1);
}

static void
mcp_cpg_destroy(gpointer user_data)
{
    crm_crit("Lost connection to cluster layer, shutting down");
    crm_exit(CRM_EX_DISCONNECT);
}

/*!
 * \internal
 * \brief Process a CPG message (process list or manual peer cache removal)
 *
 * \param[in] handle     CPG connection (ignored)
 * \param[in] groupName  CPG group name (ignored)
 * \param[in] nodeid     ID of affected node
 * \param[in] pid        Process ID (ignored)
 * \param[in] msg        CPG XML message
 * \param[in] msg_len    Length of msg in bytes (ignored)
 */
static void
mcp_cpg_deliver(cpg_handle_t handle,
                 const struct cpg_name *groupName,
                 uint32_t nodeid, uint32_t pid, void *msg, size_t msg_len)
{
    xmlNode *xml = string2xml(msg);
    const char *task = crm_element_value(xml, F_CRM_TASK);

    crm_trace("Received CPG message (%s): %.200s",
              (task? task : "process list"), (char*)msg);

    if (task == NULL) {
        if (nodeid == local_nodeid) {
            crm_debug("Ignoring message with local node's process list");
        } else {
            uint32_t procs = 0;
            const char *uname = crm_element_value(xml, "uname");

            crm_element_value_int(xml, "proclist", (int *)&procs);
            if (update_node_processes(nodeid, uname, procs)) {
                update_process_clients(NULL);
            }
        }

    } else if (crm_str_eq(task, CRM_OP_RM_NODE_CACHE, TRUE)) {
        int id = 0;
        const char *name = NULL;

        crm_element_value_int(xml, XML_ATTR_ID, &id);
        name = crm_element_value(xml, XML_ATTR_UNAME);
        reap_crm_member(id, name);
    }

    if (xml != NULL) {
        free_xml(xml);
    }
}

static void
mcp_cpg_membership(cpg_handle_t handle,
                    const struct cpg_name *groupName,
                    const struct cpg_address *member_list, size_t member_list_entries,
                    const struct cpg_address *left_list, size_t left_list_entries,
                    const struct cpg_address *joined_list, size_t joined_list_entries)
{
    /* Update peer cache if needed */
    pcmk_cpg_membership(handle, groupName, member_list, member_list_entries,
                        left_list, left_list_entries,
                        joined_list, joined_list_entries);

    /* Always broadcast our own presence after any membership change */
    update_process_peers();
}

static gboolean
mcp_quorum_callback(unsigned long long seq, gboolean quorate)
{
    pcmk_quorate = quorate;
    return TRUE;
}

static void
mcp_quorum_destroy(gpointer user_data)
{
    crm_info("connection lost");
}

int
main(int argc, char **argv)
{
    int rc;
    int flag;
    int argerr = 0;

    int option_index = 0;
    gboolean shutdown = FALSE;

    uid_t pcmk_uid = 0;
    gid_t pcmk_gid = 0;
    struct rlimit cores;
    crm_ipc_t *old_instance = NULL;
    qb_ipcs_service_t *ipcs = NULL;
    static crm_cluster_t cluster;

    crm_log_preinit(NULL, argc, argv);
    crm_set_options(NULL, "mode [options]", long_options, "Start/Stop Pacemaker\n");
    mainloop_add_signal(SIGHUP, pcmk_ignore);
    mainloop_add_signal(SIGQUIT, pcmk_sigquit);

    while (1) {
        flag = crm_get_option(argc, argv, &option_index);
        if (flag == -1)
            break;

        switch (flag) {
            case 'V':
                crm_bump_log_level(argc, argv);
                break;
            case 'f':
                /* Legacy */
                break;
            case 'p':
                pid_file = optarg;
                break;
            case 's':
                set_daemon_option("node_start_state", "standby");
                break;
            case '$':
            case '?':
                crm_help(flag, CRM_EX_OK);
                break;
            case 'S':
                shutdown = TRUE;
                break;
            case 'F':
                printf("Pacemaker %s (Build: %s)\n Supporting v%s: %s\n", PACEMAKER_VERSION, BUILD_VERSION,
                       CRM_FEATURE_SET, CRM_FEATURES);
                crm_exit(CRM_EX_OK);
            default:
                printf("Argument code 0%o (%c) is not (?yet?) supported\n", flag, flag);
                ++argerr;
                break;
        }
    }

    if (optind < argc) {
        printf("non-option ARGV-elements: ");
        while (optind < argc)
            printf("%s ", argv[optind++]);
        printf("\n");
    }
    if (argerr) {
        crm_help('?', CRM_EX_USAGE);
    }


    setenv("LC_ALL", "C", 1);

    set_daemon_option("mcp", "true");

    crm_log_init(NULL, LOG_INFO, TRUE, FALSE, argc, argv, FALSE);

    crm_debug("Checking for old instances of %s", CRM_SYSTEM_MCP);
    old_instance = crm_ipc_new(CRM_SYSTEM_MCP, 0);
    crm_ipc_connect(old_instance);

    if (shutdown) {
        crm_debug("Terminating previous instance");
        while (crm_ipc_connected(old_instance)) {
            xmlNode *cmd =
                create_request(CRM_OP_QUIT, NULL, NULL, CRM_SYSTEM_MCP, CRM_SYSTEM_MCP, NULL);

            crm_debug(".");
            crm_ipc_send(old_instance, cmd, 0, 0, NULL);
            free_xml(cmd);

            sleep(2);
        }
        crm_ipc_close(old_instance);
        crm_ipc_destroy(old_instance);
        crm_exit(CRM_EX_OK);

    } else if (crm_ipc_connected(old_instance)) {
        crm_ipc_close(old_instance);
        crm_ipc_destroy(old_instance);
        crm_err("Pacemaker is already active, aborting startup");
        crm_exit(CRM_EX_FATAL);
    }

    crm_ipc_close(old_instance);
    crm_ipc_destroy(old_instance);

    if (mcp_read_config() == FALSE) {
        crm_notice("Could not obtain corosync config data, exiting");
        crm_exit(CRM_EX_UNAVAILABLE);
    }

    // OCF shell functions and cluster-glue need facility under different name
    {
        const char *facility = daemon_option("logfacility");

        if (facility && safe_str_neq(facility, "none")) {
            setenv("HA_LOGFACILITY", facility, 1);
        }
    }

    crm_notice("Starting Pacemaker %s "CRM_XS" build=%s features:%s",
               PACEMAKER_VERSION, BUILD_VERSION, CRM_FEATURES);
    mainloop = g_main_loop_new(NULL, FALSE);

    rc = getrlimit(RLIMIT_CORE, &cores);
    if (rc < 0) {
        crm_perror(LOG_ERR, "Cannot determine current maximum core size.");
    } else {
        if (cores.rlim_max == 0 && geteuid() == 0) {
            cores.rlim_max = RLIM_INFINITY;
        } else {
            crm_info("Maximum core file size is: %lu", (unsigned long)cores.rlim_max);
        }
        cores.rlim_cur = cores.rlim_max;

        rc = setrlimit(RLIMIT_CORE, &cores);
        if (rc < 0) {
            crm_perror(LOG_ERR,
                       "Core file generation will remain disabled."
                       " Core files are an important diagnostic tool, so"
                       " please consider enabling them by default.");
        }
    }

    if (crm_user_lookup(CRM_DAEMON_USER, &pcmk_uid, &pcmk_gid) < 0) {
        crm_err("Cluster user %s does not exist, aborting Pacemaker startup", CRM_DAEMON_USER);
        crm_exit(CRM_EX_NOUSER);
    }

    mkdir(CRM_STATE_DIR, 0750);
    mcp_chown(CRM_STATE_DIR, pcmk_uid, pcmk_gid);

    /* Used to store core/blackbox/scheduler/cib files in */
    crm_build_path(CRM_PACEMAKER_DIR, 0750);
    mcp_chown(CRM_PACEMAKER_DIR, pcmk_uid, pcmk_gid);

    /* Used to store core files in */
    crm_build_path(CRM_CORE_DIR, 0750);
    mcp_chown(CRM_CORE_DIR, pcmk_uid, pcmk_gid);

    /* Used to store blackbox dumps in */
    crm_build_path(CRM_BLACKBOX_DIR, 0750);
    mcp_chown(CRM_BLACKBOX_DIR, pcmk_uid, pcmk_gid);

    // Used to store scheduler inputs in
    crm_build_path(PE_STATE_DIR, 0750);
    mcp_chown(PE_STATE_DIR, pcmk_uid, pcmk_gid);

    /* Used to store the cluster configuration */
    crm_build_path(CRM_CONFIG_DIR, 0750);
    mcp_chown(CRM_CONFIG_DIR, pcmk_uid, pcmk_gid);

    // Don't build CRM_RSCTMP_DIR, pacemaker-execd will do it

    ipcs = mainloop_add_ipc_server(CRM_SYSTEM_MCP, QB_IPC_NATIVE, &mcp_ipc_callbacks);
    if (ipcs == NULL) {
        crm_err("Couldn't start IPC server");
        crm_exit(CRM_EX_OSERR);
    }

    /* Allows us to block shutdown */
    if (cluster_connect_cfg(&local_nodeid) == FALSE) {
        crm_err("Couldn't connect to Corosync's CFG service");
        crm_exit(CRM_EX_PROTOCOL);
    }

    if(pcmk_locate_sbd() > 0) {
        setenv("PCMK_watchdog", "true", 1);
    } else {
        setenv("PCMK_watchdog", "false", 1);
    }

    switch (find_and_track_existing_processes()) {
        case -1:
            crm_crit("Internal fatality, see the log");
            crm_exit(CRM_EX_FATAL);
        case -2:
            crm_crit("Blocked by foreign process, kill the offender");
            crm_exit(CRM_EX_CANTCREAT);
        default:
            break;
    };

    cluster.destroy = mcp_cpg_destroy;
    cluster.cpg.cpg_deliver_fn = mcp_cpg_deliver;
    cluster.cpg.cpg_confchg_fn = mcp_cpg_membership;

    crm_set_autoreap(FALSE);

    rc = pcmk_ok;

    if (cluster_connect_cpg(&cluster) == FALSE) {
        crm_err("Couldn't connect to Corosync's CPG service");
        rc = -ENOPROTOOPT;

    } else if (cluster_connect_quorum(mcp_quorum_callback, mcp_quorum_destroy)
               == FALSE) {
        rc = -ENOTCONN;

    } else {
        local_name = get_local_node_name();
        update_node_processes(local_nodeid, local_name, get_process_list());

        mainloop_add_signal(SIGTERM, pcmk_shutdown);
        mainloop_add_signal(SIGINT, pcmk_shutdown);

        init_children_processes();

        crm_notice("Pacemaker daemon successfully started and accepting connections");
        g_main_loop_run(mainloop);
    }

    if (ipcs) {
        crm_trace("Closing IPC server");
        mainloop_del_ipc_server(ipcs);
        ipcs = NULL;
    }

    g_main_loop_unref(mainloop);

    cluster_disconnect_cpg(&cluster);
    cluster_disconnect_cfg();

    crm_exit(crm_errno2exit(rc));
}
